1. Field of the Invention
The present invention relates to a technology for reducing crosstalk noise between signal wires in a semiconductor apparatus, such as a solid-state image sensing device and the like.
2. Description of the Prior Art
Some semiconductor apparatus, such as a solid-state image sensing device, a liquid crystal displaying device, semiconductor memory and the like, comprises a plurality of driver circuits, a plurality of types of control signal wires connected to the driver circuits, for transmitting control signals and a group of elements which are connected to the plurality of types of control signal wires and driven by the driver circuits.
Such a semiconductor apparatus always has the problem of crosstalk between signal wires and a mis-operation due to it. This problem is described below using a solid-state image sensing device as an example.
As described in the following Patent reference 1 and Patent reference 2, a solid-state image sensing device, such as a complementary metal-oxide semiconductor (CMOS) image sensor or the like, has an array of pixels which are composed of a photo diode and a plurality of transistors, a shift register for specifying a pixel to read and a driver circuit for controlling the transistors of each pixel and the like which are disposed around the pixels, and control signal wires are wired in the array.
With the development of a semiconductor integrated circuit technology, the size of the pixel of the solid-state image sensing device has decreased and an array size has increased beyond a mega-pixel (that is, one side of the array has got long. Then, crosstalk easily occurs between control signals in the pixel.
When the control signal of the first control wire in the pixel changes, crosstalk noise occurs in the second control signal wire installed adjacently to the first control wire, and the second control signal sometimes changes unintentionally.
For example, if the first and second control signals are a charge transfer control signal and a pixel reset signal, respectively, the pixel reset signal resets a stored signal unintentionally and an output image degrades. Since the degree of this phenomenon varies depending on a distance from a driver in the pixel array, the output image obtains a shading characteristic.
Prior technical literatures related to the present invention are introduced below.
As described above, each of Patent Reference 1 and Patent Reference 2 discloses a solid-state image sensing device. Patent Reference 1 relates to a technology for expanding the dynamic range of a sensor in a solid-state image sensing device to a high-illuminance side or the like. Although as to noise in an image sensor, it discloses reset noise caused when initializing signal charge, it does not disclose crosstalk between control signals in a pixel.
Patent Reference 2 discloses that the number of wires is reduced in a solid-state image sensor. The solid-state image sensor described in Patent Reference 2 is provided with a shift register for selecting a pixel located in the vertical direction, on each side of a pixel array. However, even Patent Reference 2 fails to disclose crosstalk between control signals in the pixel.
Patent Reference 3 relates to a liquid crystal display and discloses that a compensation voltage application circuit is provided on the opposite side of a signal driver across a liquid crystal display device in order to solve a problem that display variation (crosstalk) occurs on a screen. In Patent Reference 3 too, pixels are disposed in array and signal wires are wired, but it fails to disclose crosstalk problem between signal wires.
As described above, conventionally, as measures for reducing crosstalk between signal wires, a sufficient distance is secured between signal wires in a design stage. Or, countermesure at each element in a semiconductor apparatus is considered for preventing mis-operation due to crosstalk. However, such measures lead to increase a chip area and to increase the size of the semiconductor apparatus, which is not favorable.
It is not preferable to adopt such crosstalk reduction measures that increase the number of wires in the semiconductor apparatus, or interfere with the logic for driving each element in the semiconductor apparatus and restrict the driving logic.
Patent reference 1: Japanese Published Patent Application No. 2004-159274
Patent reference 2: Japanese Published Patent Application No. 2003-134399
Patent reference 3: Japanese Published Patent Application No. H08-129158